Re: can somone identify the type of fresnel lens I have?

In article <HHnBi.12085$Zg.2273@trnddc08>, "Jason Abernathy" <jabert@xxxxxxx> wrote:
Just acquired a 41x31 inch fresnel lens made by DNP. The number on the lens
is 491P043A90. What type of lens is this specifically (linear fresnel,
etc)?

Thanks, in advance, for your help.

Jason



I can't guarantee that any of this is correct... Given those dimensions, it
sound to me like it may be from a video projection screen of some sort. I used
to laser trim large fresnel's of similar dim's for Electrosonic's video cubes.
These are the large boxed up projectors/screens that are stacked up to make
videowalls for concerts, etc. Each one has a diffuser and a fresnell lens in
them, and the 4x3 ratio of the dim. is very close to the standard video
ratios. Again, just a guess. If I remember right, the focal length of most of
these type screens is about 43 inches, and some of them are also off axis.
Pioneer Elect. of Japan also makes similar cubes, but it could also be from
any number of manu. that makes consumer home type projection flat screen
tv's. Again, just a guess..

d.
.

Relevant Pages

  • Re: How rare are curved cinemascope screens?
    ... further from the projector lens than the center. ... that the real world projection optics result in a curving focal plane. ... manifestation of how all lenses are (unless the design specifically alters ... for flat screens. ...
    (rec.arts.movies.tech)
  • Re: Focus calibration
    ... AF sensors and imaging sensor are at different ... Yes, the AF system gets the focus perfect and the lens either backtracks or continues as the mirror rises, to a position which is not exactly that of the AF focused point. ... The latest lenses have more accurate distance encoding and can be adjusted better. ... So adjusting the dioptre for dead sharp view of the focus markings may not mean you are focusing on the screen itself, and with modern semi-clear screens, that can lead to poor manual focusing accuracy. ...
    (rec.photo.digital.slr-systems)
  • Re: Connecting EOS 10D to Zeiss ICM 405
    ... the distance between eyepiece/relay lens and camera ccd, ... projection distance is different from the distance it is designed for. ... looking for the most suitable camera from the outset. ...
    (sci.techniques.microscopy)
  • Re: Poll on *Really* Wide Angle Lenses
    ... >No, BC is correct here, at least as far as flat-field rectilinear ... A fisheye lens has the first property, but not the second (except in the ... Most people seem to find the rectilinear projection less aestetically ... It's not possible to do this in a photograph, ...
    (rec.photo.digital)
  • Re: lens choice for high res video camera
    ... > with optics and can't get clear which lens to use. ... > The camera used is an Adimec 4020m with a resolution of 2048*2048 pix. ... > problems with "seeing thru" the projection foil (seen in experiments ... the area of your sensor, though, should be very low. ...
    (sci.optics)